Anatomy and Physiology of the Salivary Glands

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Anatomy and Physiology of the Salivary Glands

• Frederick S. Rosen, MD
• Byron J. Bailey, MD
• January 24, 2001

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Introduction

• The Major Salivary Glands
• Parotid
• Submandibular
• Sublingual
• The Minor Salivary Glands

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Embryology

• 6th-8th Weeks of Gestation
• Parotid
• First to develop
• Last to become encapsulated
• Autonomic Nervous System Crucial

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Embryology
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Anatomy Parotid Gland

• Wedge shaped with 5 processes
• 3 Superficial
• 2 Deep
• Parotid Compartment
• Superior Zygoma
• Posterior EAC
• Inferior Styloid, ICA, Jugular Veins

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Anatomy Parotid Gland

• 80 overlies Masseter Mandible
• 20 Retromandibular
• Stylomandibular Tunnel, Isthmus of Parotid
• Tail of Parotid

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Anatomy Parotid Gland

• Parapharyngeal Space
• Prestyloid Compartment
• Poststyloid Compartment (Paragangliomas)

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Anatomy Parotid Gland

• Stensens Duct
• Arises from anterior border
• 1.5 cm inferior to Zygomatic arch
• Pierces Buccinator at 2nd Molar
• 4-6 cm in length
• 5 mm in diameter

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Anatomy Parotid Gland

• Parotid Capsule
• Superficial layer Deep Cervical Fascia
• Superficial layer
• Deep layer

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Anatomy Parotid Gland

• CN VII
• 2 Surgical zones
• 3 Motor branches immediately
• Pes Anserinus 1.3 cm
• Temperofacial Division
• Cervicofacial Division
• 5 Terminal branches

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Anatomy Parotid Gland
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Anatomy Parotid Gland

• Localization of CN VII
• Tragal pointer
• Tympanomastoid suture
• Posterior belly Digastric
• Styloid process
• Retrograde dissection
• Mastoidectomy

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Anatomy Parotid Gland

• Great Auricular nerve
• Auriculotemporal nerve
• Superficial Temporal vessels
• Freys Syndrome

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Anatomy Parotid Gland

• Neural compartment
• VII, Great Auricular, Auriculotemporal
• Venous compartment
• Retromandibular vein
• Arterial compartment
• Superficial Temporal/Transverse Facial

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Anatomy Parotid Gland

• Lymphatics
• Paraparotid Intraparotid nodes
• Superficial Deep Cervical nodes

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Anatomy Submandibular Gland

• The Submaxilla
• Submandibular Triangle
• Mylohyoid C
• Marginal Mandibular branch
• Capsule from superficial layer of Deep Cervical
  fascia

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Anatomy Submandibular Gland

• Whartons duct
• Exits medial surface
• Between Mylohyoid Hyoglossus
• 5 cm in length
• Lingual nerve CN XII

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Anatomy Submandibular Gland
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Anatomy Submandibular Gland

• Innervation
• Superior Cervical Ganglion (symp)
• Submandibular Ganglion (para)
• Artery Submental branch of Facial a.
• Vein Anterior Facial vn.
• Lymphatics Deep Cervical and Jugular chains
• Facial artery nodes

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Anatomy Sublingual Gland

• Between Mandible Genioglossus
• No capsule
• Ducts of Rivinus /- Bartholins duct
• Sialogram not possible
• Innervation Same as Submandibular
• Artery/Vein Sublingual branch of Lingual
  Submental branch of Facial
• Lymphatics Submandibular nodes

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Anatomy Sublingual Gland
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Anatomy Minor Salivary Glands

• 600-1,000
• Simple ducts
• Buccal, Labial, Palatal, Lingual
• Tumor sites Palate, upper lip, cheek
• Lingual Palatine nn.

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Imaging

• CT Inflammatory
• MR Tumor
• Children U/S MR
• NO sialogram during active infection
• Parotid is fatty

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Microanatomy

• The Secretory Unit
• Acinus (serous, mucous, mixed)
• Myoepithelial cells
• Intercalated duct
• Striated duct
• Excretory duct

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Microanatomy

• Striated Intercalated ducts well developed in
  serous, NOT mucous glands
• Striated duct HCO3 into, Cl from lumen
• Intercalated duct K into lumen, Na from lumen,
  producing hypotonic fluid
• Excretory ducts do NOT modify saliva

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Microanatomy
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Microanatomy

• The Bicellular Theory
• Intercalated duct
• Excretory duct
• The Multicellular Theory

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Microanatomy

• Parotid serous fatty
• Submandibular mixed serous
• Sublingual mixed mucous
• Stroma Plasma cells

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Microanatomy
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Microanatomy
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Function of Saliva

• Moistens oral mucosa
• Moistens cools food
• Medium for dissolved food
• Buffer (HCO3)

• Digestion (Amylase, Lipase)
• Antibacterial (Lysozyme, IgA, Peroxidase, FLOW)
• Mineralization
• Protective Pellicle

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Function of Saliva

• Salivary hypofunction
• Candidiasis
• Lichen Planus
• Burning Mouth
• Aphthous ulcers
• Dental caries
• Xerostomia not reliable

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Production of Saliva

• Primary secretion
• Ductal secretion
• The secretory potential (hyperpolarizes)
• Increased flow rate yields decreased hypotonicity
  K

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Autonomic Innervation

• Parasympathetic
• Abundant, watery saliva
• Amylase down
• Sympathetic
• Scant, viscous saliva
• Amylase up

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Salivary Flow

• 1-1.5 L/day (1 cc/min)
• Unstimulated state
• Submandibular
• Stimulated state
• Parotid
• Sublingual minor
• Mucin

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Effects of Aging

• Total salivary flow independent of age
• Acinar cells degenerate with age
• Submandibular gland more sensitive to
  metabolic/physiologic change
• Unstimulated salivary flow more greatly affected
  by physiologic changes